Fast 5K Key #4: Slow Down Your Distance Runs

Fast 5K: 25 Crucial Keys and 4 Training Plans by Pete Magill is your guide to your fastest 5K race. Celebrated running coach Magill shares the essential keys to 5K fitness and race readiness and offers four training plans to prepare you for race day.

Key #4: Slow Down Your Distance Runs

“Good things come slow, especially in distance running.” —Bill Dellinger, Olympian and five-time NCAA championship coach


Distance runs are the primary way you train slow-twitch muscle fibers.

Most runners understand that it’s the cumulative volume of distance runs that provides the foundation for success as a distance runner. That’s true whether you’re training for a 5K or a marathon. That said, runners make a mistake when they assume that up-tempo distance runs are more effective than runs performed at a comfortable effort level. In fact, many runners sabotage their training by doing their distance runs too hard.

First, let’s dispel a running myth: Running your distance runs slowly won’t make you a slow runner. Training incorrectly—not doing the full range of workouts required to build speed—will make you a slow runner.

The correct pace for your distance runs is the pace that guarantees you’ll get 100 percent of the benefits you’re hoping to reap from those runs. So step one (as with any workout) is to determine those targeted benefits. For distance runs, the training adaptations you’re after include:

  • Strengthening slow-twitch muscle fibers
  • Strengthening connective tissue like bones and tendons
  • Increasing the number and size of mitochondria (microscopic, aerobic energy–producing power plants) within each slow-twitch fiber
  • Increasing the number of capillaries surrounding each slow-twitch fiber (capillaries are tiny blood vessels that carry oxygen and nutrients to your muscle fibers)
  • Increasing the amount of carbohydrate fuel (i.e., glycogen) stored within each slow-twitch fiber
  • Strengthening your heart, so that you can pump more blood with each heartbeat
  • Improving your nervous system’s ability to recruit slow-twitch fiber into action, thereby creating a more efficient stride and reducing the amount of energy you’ll expend

To trigger all these adaptations, you need to run at about 65–75 percent VO2max. In layman’s terms, that means running at a conversational pace—about two minutes per mile slower than 5K pace for faster runners, and up to three minutes per mile for slower runners. At that effort level, your body receives the correct stimulus. Equally important, you’ll recover in time for the next day’s workout. Run harder than that, and you recruit faster fibers, creating nervous-system fatigue and increasing your use of anaerobic energy, both of which lengthen the time you’ll need for recovery. See the Training Paces table in the book for pacing guidelines.

If you’re still having trouble keeping your foot off the accelerator, try leaving your watch at home. If you know how far a run is, you don’t need to time it. Going watchless removes the temptation to speed up and allows you to settle into a pace that’s appropriate for the day—one that matches your fatigue level, the temperature, that stiff lower back from sitting at a desk for eight hours, or some other variable that might affect your pace on that specific day.

My own watchless running began in my mid-40s. I’d been doing the same recovery run for years, and my time had gradually slipped from 45 minutes to 50 minutes. It was depressing. I decided, Enough! and left the watch at home the next time I did that run. At the end of the run, my son Sean admitted he’d timed me. “You ran 62 minutes,” he said. Turned out, I’d been running too fast all along. After that day, I stopped wearing a watch for distance runs. I slowed my pace. Recovered better. Was stronger on hard days. And saw my race times drop.

Distance runs will make up the bulk of your training volume. And long-term improvement is largely dictated by the accumulation of these runs. But the emphasis is on “long-term.” We’re talking months and years, not days and weeks.

In the meantime, running distance faster than necessary won’t shortcut the process or earn you a faster 5K. Instead, it will leave you tired, heavy-legged, unprepared for the next day’s workout, and slower on race day.

Fast 5K: 25 Crucial Keys and 4 Training Plans by Pete Magill is your guide to your fastest 5K race. Celebrated running coach Magill shares the essential keys to 5K fitness and race readiness and offers four training plans to prepare you for race day.